Swimming pools are a convenient source of recreation and exercise for many people. For those fortunate enough to have a private pool at their own residence, the convenience is even greater. However, this facility also requires a great deal of cleaning to keep it free from dirt and bacterial growth. The desirability of the pool decreases greatly if it is dirty or has algae growing. Unfortunately, due to the large size of such a pool and its openness, it is subject to receiving a great deal of dirt and other foreign material which is carried by the wind, dropped by nearby vegetation, or carried into the water by its users.
The foreign material may be left floating on the water, as in the case of leaves, may be dissolved in the water, or may eventually deposit on the floor of the swimming pool. Some dirt may be removed from the water by the action of the filtering pumps which remove the water, filter it, and return it to the pool. Debris which is floating on the surface of the water may be removed using a skimmer, either in the form a long pole with a net on the end, or by an automated system. However, a more difficult situation is removal of material from the floor of the pool. A common way to remove this material is to utilize a suction device which is carried across the floor of the pool. One simple method of doing this is to utilize a long pole carrying a suction head which is connected to a pump by way of a long hose. As water is drawn into the suction head, it picks up the dirt, as long as the head is in close proximity to the floor of the pool. While this is efficient in terms of the control of the location of the head, it requires the physical effort and concentration of an operator.
Other devices can also be used to clean the floor of the pool which do not require the attendance and efforts of an operator. Such devices include typically a wheeled vehicle which travels along the floor and which carries a suction head. The suction head may be connected to a separate vacuum source by way of a hose or may merely use a self-contained filter so that the cleaned water may be returned to the pool. While this type of device does not require the attention and effort of an operator, it is necessary that it be directed to cover the entire area of the pool bottom. One way of doing this is to have some type of programmed pattern so that the pool bottom is completely covered by the cleaning device. However, this type of system is difficult to program because of the varying sizes and shapes of pools. Also, since the device is not intelligent, it is easy to be dislodged from the desired pattern and once dislodged, the entire bottom would not be cleaned.
One manner of avoiding the problem of following a pattern is to allow the device to merely act randomly, so that given sufficient time, the entire floor would be cleaned. This is typically accomplished by allowing the device to proceed along the floor and to reverse direction when it comes into contact with the wall. However, this would require that the course be changed when it is reversed so that it will not merely go back and forth over the same path. One manner of changing the course is to have a switch which is actuated when a bumper or other part of the cleaner comes into contact with the wall. When the wall is contacted, the switch is activated and some mechanism is used to physically move the device or to lift up one side so that a course change is generated from the wheels in contact with the ground. Such a mechanism requires additional power and additional structure in order for it operate. It also has a problem that continued bumping into a straight wall may cause damage to the cleaner. Also, the additional mechanism is subject to maintenance needs and repairs.
Another way of changing the direction of such a cleaner, is to allow the device to continue pushing even when it hits a wall at an angle, so that it becomes square to the wall before reversing. This would change its direction from an angle to the wall to the perpendicular to that wall. However, if the unit initially contacts the wall at a 90° angle, it then merely reverses into the same path, which is not desirable. This would allow the cleaning device to run back and forth in the same path from side-to-side without cleaning the entire floor.
Other problems are also present in such pool cleaners. When the cleaning operation is finished, the cleaning unit should be removed from the pool. However, since it is full of water, it can be quite heavy to lift and further, it is desirable to drain the water from the inside without disturbing the dirt which has been collected. One system which is previously been used is to provide a rubber or elastic vinyl flap on the sides of the cleaner which swing outwardly to allow the water to drain. These flaps would not open when the device is in water, because the pressure on either side would be equalized. However, when the cleaner is removed from the water, any water contained inside would be heavier then the air outside the flap and accordingly the flap would open, allowing the water to drain out. While this system will work, the flaps tend to be deformed after a period of time so that the doors do not seal properly.
Doors are usually provided on the bottom of the device to allow the water which is being suctioned up to easily flow therein. Thus, the doors swing inwardly to allow water to rise from the bottom of the pool into the inside of the unit. When the unit is removed from the water, water could not flow out this door unless it is tilted to the side. This is desirable to prevent captured dirt from being returned to the pool.
Other problems can be involved with such a cleaning system. It is important for the motor which drives the system to be waterproofed and still to allow heat to escape from the motor and other components. In this manner, it is also necessary to have watertight connections with electrical wiring connected to the pump.